Process for the manufacture of xylenes



Patented Sept. 10, 1929.

UNITED STATES EDUARD 'rscnonxuza, or COLOGNE, MULHEIM, AND FRITZ EIG LER, or LEVERKU- 'sEN-oN-TEE-EHINE, GERMANY, ASSIGNORS TO GENERAL ANILINE woaxs, mo.

PATENT OFFICE.

OF NEW YOBK,,N. Y., A CORPORATION OF DELAWARE.

PROCESS FOR THE KANUFACTURE F ZYLENES.

Ne Drawing. Application filed September 15, 1927, Serial No. 219,803, and in Germany August 10, 1926.

This invention relates to a process for the manufacture of oand p-xylene.

' Technical xylene, which is obtained together with benzene and toluene by the coking of coal, consists mainly of m-xylene,w1th

a small quantity of oand p-xylenc, besides these ethylbenzene, trimeth l benzene and higher homologues, fatty acid hydrocarbons and other impurities, the nature of wluch 1s v [0 not fully established, are also present. Thus there is an abundant supply of m-xylene, but not of 0- and p-xylene whose production has hitherto been attended with considerable difiiculties. The isolation of the small quantity of oand p-xylene from technical xylene is rendered difiicult by the numerous tic reduction with hydrogen into the corrcspending 0- and p-xylene.

The separation and purification of the pand o-xylene may be readily effected by fractional distillation.

The separation of o-xylene from p-xylene can also be effected by sulfonation, since 0- xylene is much more readily s'ulfonated than p-xvlene.

The present invention accordingly provides a new process for the manufacture of oand p-xylone in any quantity, which is both technically convenient and economical, whereas hitherto these compounds could only be obtained in limited quantities and with great difliculty and expense.

The following examples will illustrate the invention:

Emmnple 1.368 kilograms of toluene, 200

litres of hydrochloric acid and kilograms of paraformaldehyde (which may be replaced by the corresponding quantity of 40% farmaldehyde') are heated to about 60 C. in a lead lined or acid proof vessel and a vigorous current of hydrochloric acid gas is passed through under vigorous stirring. The reaction is complete after about 36 to 40 hours (the end of the reaction is ascertained by testing for the presence of formaldehyde in the acid liquor). When the reaction is complete the upper layer containing toluene and oand p-xylyl chloride is separated from the hydrochloric acid layer and converted by reduction into a mixture of toluene and oand p-xylene as above indicated. The resulting mixture can be separated from the toluene by fractional distillation and o-xylene and p-xylene obtained of a satisfactory purit As already stated (after the distillation of toluene) the o-xylene can be separated and obtained pure from p-xylene by sulfonation and subsequent hydrolyzing of the sulfonic acids produced.

EmampZe,2. -Into a mixture of 800 kilograms of toluene, 60 kilograms of paraformaldehyde and 30 kilograms of zinc chloride or stannic tetrachloride SnCl, a current of HCl is introduced at 60 C. When the HGl gas is no longer absorbed a solution of sodium carbonate is added and from the aqueous layer which is separated orthoand para-xylene are isolated as stated in Exam Is 1.

e claim:

1. In the process for the manufacture of oand p-xylenes, the steps comprising treating toluene with formaldehyde in the presence of hydrochloric acid and reducing the resulting mixture of oand p-xylyl chlorides to the corresponding xylenes. i

2. Process for the manufacture of xylenes as claimed in claim 1, in which the condensation treatment is effected in the pres ence of a condensing agent.

In testimony 'whereofwe have hereunto set our hands.

- EDUARD TSCHUNKUR;

FRITZ EICHLER. 

